Figure 5.
Polymerization model for Mfa1 fimbriae. Mfa1, Mfa3, and Mfa4 are transported to the periplasmic space via the Sec system in the inner membrane (Hasegawa and Murakami 2014) and thereafter across the outer membrane. β1-strands at the N-termini of Mfa1, Mfa3, and Mfa4 are processed by gingipains, and the resulting Nmature strands are inserted into neighboring Mfa1, Mfa3, and Mfa4 based on a donor-strand complementation mechanism (Kloppsteck et al. 2016). In this report, we demonstrated that Mfa5 is transported through the outer membrane via the type IX secretion system via C-terminal domain (CTD) recognition, the CTD is removed by PorU, and the mature protein may be incorporated into Mfa1 fimbriae through von Willebrand factor type A (VWA)–mediated interactions. Modified from (Kloppsteck et al. 2016).